From: Phillip Wood <phillip.wood123@gmail.com>
To: "SZEDER Gábor" <szeder.dev@gmail.com>, git@vger.kernel.org
Cc: Junio C Hamano <gitster@pobox.com>,
Johannes Schindelin <Johannes.Schindelin@gmx.de>
Subject: Re: minor interactive rebase regression: HEAD points to wrong commit while rewording
Date: Mon, 12 Aug 2019 21:28:52 +0100 [thread overview]
Message-ID: <2a7d69a9-cb3e-eb84-188f-5713876f6d78@gmail.com> (raw)
In-Reply-To: <20190812175046.GM20404@szeder.dev>
On 12/08/2019 18:50, SZEDER Gábor wrote:
>
> When running interactive rebase to reword a commit message, I would
> expect that the commit whose message I'm rewording is checked out.
> This is not quite the case when rewording multiple subsequent commit
> messages.
>
> Let's start with four commits, and start an interactive rebase from
> the first commit:
>
> $ git log --oneline
> 5835aa1 (HEAD -> master) fourth
> 64ecc64 third
> d5fad83 second
> 384b86f first
> $ git rebase -i 384b86f
>
> Update the instruction sheet to edit the log messages of two
> subsequent commits:
>
> r d5fad83 second
> r 64ecc64 third
> pick 5835aa1 fourth
>
> Now, after the editor opens up the second commit's log message, start
> a new terminal and check where HEAD is pointing to:
>
> ~/tmp/reword (master|REBASE-i 1/3)$ head -n1 .git/COMMIT_EDITMSG
> second
> ~/tmp/reword (master|REBASE-i 1/3)$ git log --oneline -1
> d5fad83 (HEAD) second
>
> So far so good.
Because the sequencer can fast-forwarded to second from first it does
that and then run 'commit --amend' to do the reword.
> Save the updated commit message, and after the editor opens up the
> third commit's log message, check again where HEAD is pointing to now:
>
> ~/tmp/reword (master +|REBASE-i 2/3)$ head -n1 .git/COMMIT_EDITMSG
> third
> ~/tmp/reword (master +|REBASE-i 2/3)$ git log --oneline -1
> c3db735 (HEAD) second - updated
As second has been updated the sequencer cannot fast-forward to third so
it cherry-picks third and then passes --edit when it runs 'git commit'
to commit the cherry-pick. HEAD is updated once the reworded commit has
been created.
I think the scripted rebase always ran cherry-pick and then ran 'commit
--amend' afterwards if the commit was being reworded. The C
implementation is more efficient as it avoids creating an redundant
commit but has the side effect that HEAD is not updated before the
reword which was surprising here.
I don't think I've ever looked at HEAD while rewording, my shell prompt
gets the current pick from .git/rebase-merge/done so does not look at
HEAD. While it might seem odd if the user looks at HEAD it's quite nice
not to create a new commit only to amend it straight away when it's
reworded. We have REBASE_HEAD which always points to the current pick -
HEAD is also an unreliable indicator of the current pick if there are
conflicts.
Best Wishes
Phillip
> As you can see, HEAD still points to the (now rewritten) second
> commit.
>
> It's only HEAD, though: notice the '+' in the git prompt, indicating
> that both the worktree and index are dirty. And indeed, they both
> already match the state of the currently reworded, i.e. third, commit:
>
> ~/tmp/reword (master +|REBASE-i 2/3)$ cat file
> third
>
> This is good, because even though HEAD has not been updated yet, it
> already allows users to take a look at the "big picture", i.e. actual
> file contents, in case the diff included in the commit message
> template doesn't show enough context.
>
> This behavior changed in commit 18633e1a22 (rebase -i: use the
> rebase--helper builtin, 2017-02-09); prior to that HEAD pointed to the
> third commit while editing its log message.
>
> It's important to reword subsequent commits. When rewording multiple,
> but non subsequent commits (e.g. reword, pick, reword in the
> instruction sheet), then HEAD is pointing to the right commits during
> both rewords.
>
>
next prev parent reply other threads:[~2019-08-12 20:28 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-12 17:50 minor interactive rebase regression: HEAD points to wrong commit while rewording SZEDER Gábor
2019-08-12 18:17 ` Junio C Hamano
2019-08-12 18:56 ` SZEDER Gábor
2019-08-12 20:28 ` Phillip Wood [this message]
2019-08-14 20:45 ` Johannes Schindelin
2019-08-14 21:40 ` SZEDER Gábor
2019-08-14 21:20 ` SZEDER Gábor
2019-08-15 13:47 ` Phillip Wood
2019-08-15 16:36 ` Junio C Hamano
2019-08-15 16:54 ` Junio C Hamano
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: http://vger.kernel.org/majordomo-info.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=2a7d69a9-cb3e-eb84-188f-5713876f6d78@gmail.com \
--to=phillip.wood123@gmail.com \
--cc=Johannes.Schindelin@gmx.de \
--cc=git@vger.kernel.org \
--cc=gitster@pobox.com \
--cc=szeder.dev@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://80x24.org/mirrors/git.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).